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Two Groups of Thellungiella salsuginea RAVs Exhibit Distinct Responses and Sensitivity to Salt and ABA in Transgenic Arabidopsis.

Yang S, Luo C, Song Y, Wang J - PLoS ONE (2016)

Bottom Line: Under normal conditions, the germination process of all TsRAVs overexpressing transgenic seeds was inhibited with a stronger effect observed in 35S:A-TsRAVs seeds than in 35S:B-TsRAVs seeds.All 35S:TsRAVs transgenic plants showed a similar degree of reduction in root growth compared with untreated seedlings in the presence of ABA.Taken together, our results suggest that two groups of TsRAVs perform distinct regulating roles during plant growth and abiotic defense including drought and salt, and A-TsRAVs are more likely than B-TsRAVs to act as negative regulators in the above-mentioned biological processes.

View Article: PubMed Central - PubMed

Affiliation: School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.

ABSTRACT
Containing both AP2 domain and B3 domain, RAV (Related to ABI3/VP1) transcription factors are involved in diverse functions in higher plants. A total of eight TsRAV genes were isolated from the genome of Thellungiella salsuginea and could be divided into two groups (A- and B-group) based on their sequence similarity. The mRNA abundance of all Thellungiella salsuginea TsRAVs followed a gradual decline during seed germination. In Thellungiella salsuginea seedling, transcripts of TsRAVs in the group A (A-TsRAVs) were gradually and moderately reduced by salt treatment but rapidly and severely repressed by ABA treatment. In comparison, with a barely detectable constitutive expression, the transcriptional level of TsRAVs in the group B (B-TsRAVs) exhibited a moderate induction in cotyledons when confronted with ABA. We then produced the "gain-of-function" transgenic Arabidopsis plants for each TsRAV gene and found that only 35S:A-TsRAVs showed weak growth retardation including reduced root elongation, suggesting their roles in negatively controlling plant growth. Under normal conditions, the germination process of all TsRAVs overexpressing transgenic seeds was inhibited with a stronger effect observed in 35S:A-TsRAVs seeds than in 35S:B-TsRAVs seeds. With the presence of NaCl, seed germination and seedling root elongation of all plants including wild type and 35S:TsRAVs plants were retarded and a more severe inhibition occurred to the 35S:A-TsRAV transgenic plants. ABA treatment only negatively affected the germination rates of 35S:A-TsRAV transgenic seeds but not those of 35S:B-TsRAV transgenic seeds. All 35S:TsRAVs transgenic plants showed a similar degree of reduction in root growth compared with untreated seedlings in the presence of ABA. Furthermore, the cotyledon greening/expansion was more severely inhibited 35S:A-TsRAVs than in 35S:B-TsRAVs seedlings. Upon water deficiency, with a wider opening of stomata, 35S:A-TsRAVs plants experienced a faster transpirational water loss than wild type and 35S:B-TsRAVs lines. Taken together, our results suggest that two groups of TsRAVs perform distinct regulating roles during plant growth and abiotic defense including drought and salt, and A-TsRAVs are more likely than B-TsRAVs to act as negative regulators in the above-mentioned biological processes.

No MeSH data available.


Related in: MedlinePlus

Cotyledon-greening analysis on 35S:TsRAVs transgenic Arabidopsis seedlings.(A) Phenotypic comparison of wild-type and 35S:TsRAVs transgenic Arabidopsis seedlings after grown on normal 1/2 MS medium (upper panel) or on 1/2 MS medium with 0.5 μM ABA for 6 days (lower panel). (B) Cotyledon-greening percentages of 35S:TsRAVs transgenic Arabidopsis seedlings after grown on 1/2 MS medium with 0.5 μM ABA for 6 days. Each data bar represents the mean ± SE of three replicates. More than 100 seeds were measured in each replicate. Different letters indicate significant differences among means (P<0.05 by Tukey’s test).
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pone.0153517.g006: Cotyledon-greening analysis on 35S:TsRAVs transgenic Arabidopsis seedlings.(A) Phenotypic comparison of wild-type and 35S:TsRAVs transgenic Arabidopsis seedlings after grown on normal 1/2 MS medium (upper panel) or on 1/2 MS medium with 0.5 μM ABA for 6 days (lower panel). (B) Cotyledon-greening percentages of 35S:TsRAVs transgenic Arabidopsis seedlings after grown on 1/2 MS medium with 0.5 μM ABA for 6 days. Each data bar represents the mean ± SE of three replicates. More than 100 seeds were measured in each replicate. Different letters indicate significant differences among means (P<0.05 by Tukey’s test).

Mentions: It has been reported that when grown on MS plus ABA, the RAV1-overexpressing plants showed higher cotyledon-greening percentage than wild-type plants, and much lower cotyledon-greening percentages have been reported for RAV RNAi lines and rav1 mutants [15], so we also determined the green cotyledon percentages of both wild type and TsRAVs transgenic lines in the current study. As shown in Fig 6A, there was no significant difference in green cotyledon rate between TsRAVs transgenic lines and wild type on normal 1/2 MS media, just as described previously [15]. In the presence of exogenous ABA, the green seedling rates of both wild type and TsRAVs overexpressing lines were significantly decreased. Compared to WT and B-TsRAVs transgenic lines, A-TsRAVs transgenic lines had significantly fewer open and green leaves after 6 days (Fig 6A). After being treated by 0.5 μM ABA for 6 days, nearly 88% of wild type seedlings stayed green, while only 55–66% and 79–87% green seedlings was recorded for A-TsRAVs and B-TsRAVs transgenic lines, respectively (Fig 6B). Thus, the ABA-induced earlier leaf etiolation and lower chlorophyll content were much more severe in 35S:A-TsRAVs transgenic lines, suggesting that A-TsRAVs but not B-TsRAVs might be involved in the ABA-regulated photosynthesis and leaf senescence.


Two Groups of Thellungiella salsuginea RAVs Exhibit Distinct Responses and Sensitivity to Salt and ABA in Transgenic Arabidopsis.

Yang S, Luo C, Song Y, Wang J - PLoS ONE (2016)

Cotyledon-greening analysis on 35S:TsRAVs transgenic Arabidopsis seedlings.(A) Phenotypic comparison of wild-type and 35S:TsRAVs transgenic Arabidopsis seedlings after grown on normal 1/2 MS medium (upper panel) or on 1/2 MS medium with 0.5 μM ABA for 6 days (lower panel). (B) Cotyledon-greening percentages of 35S:TsRAVs transgenic Arabidopsis seedlings after grown on 1/2 MS medium with 0.5 μM ABA for 6 days. Each data bar represents the mean ± SE of three replicates. More than 100 seeds were measured in each replicate. Different letters indicate significant differences among means (P<0.05 by Tukey’s test).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4836749&req=5

pone.0153517.g006: Cotyledon-greening analysis on 35S:TsRAVs transgenic Arabidopsis seedlings.(A) Phenotypic comparison of wild-type and 35S:TsRAVs transgenic Arabidopsis seedlings after grown on normal 1/2 MS medium (upper panel) or on 1/2 MS medium with 0.5 μM ABA for 6 days (lower panel). (B) Cotyledon-greening percentages of 35S:TsRAVs transgenic Arabidopsis seedlings after grown on 1/2 MS medium with 0.5 μM ABA for 6 days. Each data bar represents the mean ± SE of three replicates. More than 100 seeds were measured in each replicate. Different letters indicate significant differences among means (P<0.05 by Tukey’s test).
Mentions: It has been reported that when grown on MS plus ABA, the RAV1-overexpressing plants showed higher cotyledon-greening percentage than wild-type plants, and much lower cotyledon-greening percentages have been reported for RAV RNAi lines and rav1 mutants [15], so we also determined the green cotyledon percentages of both wild type and TsRAVs transgenic lines in the current study. As shown in Fig 6A, there was no significant difference in green cotyledon rate between TsRAVs transgenic lines and wild type on normal 1/2 MS media, just as described previously [15]. In the presence of exogenous ABA, the green seedling rates of both wild type and TsRAVs overexpressing lines were significantly decreased. Compared to WT and B-TsRAVs transgenic lines, A-TsRAVs transgenic lines had significantly fewer open and green leaves after 6 days (Fig 6A). After being treated by 0.5 μM ABA for 6 days, nearly 88% of wild type seedlings stayed green, while only 55–66% and 79–87% green seedlings was recorded for A-TsRAVs and B-TsRAVs transgenic lines, respectively (Fig 6B). Thus, the ABA-induced earlier leaf etiolation and lower chlorophyll content were much more severe in 35S:A-TsRAVs transgenic lines, suggesting that A-TsRAVs but not B-TsRAVs might be involved in the ABA-regulated photosynthesis and leaf senescence.

Bottom Line: Under normal conditions, the germination process of all TsRAVs overexpressing transgenic seeds was inhibited with a stronger effect observed in 35S:A-TsRAVs seeds than in 35S:B-TsRAVs seeds.All 35S:TsRAVs transgenic plants showed a similar degree of reduction in root growth compared with untreated seedlings in the presence of ABA.Taken together, our results suggest that two groups of TsRAVs perform distinct regulating roles during plant growth and abiotic defense including drought and salt, and A-TsRAVs are more likely than B-TsRAVs to act as negative regulators in the above-mentioned biological processes.

View Article: PubMed Central - PubMed

Affiliation: School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.

ABSTRACT
Containing both AP2 domain and B3 domain, RAV (Related to ABI3/VP1) transcription factors are involved in diverse functions in higher plants. A total of eight TsRAV genes were isolated from the genome of Thellungiella salsuginea and could be divided into two groups (A- and B-group) based on their sequence similarity. The mRNA abundance of all Thellungiella salsuginea TsRAVs followed a gradual decline during seed germination. In Thellungiella salsuginea seedling, transcripts of TsRAVs in the group A (A-TsRAVs) were gradually and moderately reduced by salt treatment but rapidly and severely repressed by ABA treatment. In comparison, with a barely detectable constitutive expression, the transcriptional level of TsRAVs in the group B (B-TsRAVs) exhibited a moderate induction in cotyledons when confronted with ABA. We then produced the "gain-of-function" transgenic Arabidopsis plants for each TsRAV gene and found that only 35S:A-TsRAVs showed weak growth retardation including reduced root elongation, suggesting their roles in negatively controlling plant growth. Under normal conditions, the germination process of all TsRAVs overexpressing transgenic seeds was inhibited with a stronger effect observed in 35S:A-TsRAVs seeds than in 35S:B-TsRAVs seeds. With the presence of NaCl, seed germination and seedling root elongation of all plants including wild type and 35S:TsRAVs plants were retarded and a more severe inhibition occurred to the 35S:A-TsRAV transgenic plants. ABA treatment only negatively affected the germination rates of 35S:A-TsRAV transgenic seeds but not those of 35S:B-TsRAV transgenic seeds. All 35S:TsRAVs transgenic plants showed a similar degree of reduction in root growth compared with untreated seedlings in the presence of ABA. Furthermore, the cotyledon greening/expansion was more severely inhibited 35S:A-TsRAVs than in 35S:B-TsRAVs seedlings. Upon water deficiency, with a wider opening of stomata, 35S:A-TsRAVs plants experienced a faster transpirational water loss than wild type and 35S:B-TsRAVs lines. Taken together, our results suggest that two groups of TsRAVs perform distinct regulating roles during plant growth and abiotic defense including drought and salt, and A-TsRAVs are more likely than B-TsRAVs to act as negative regulators in the above-mentioned biological processes.

No MeSH data available.


Related in: MedlinePlus